The super PAC also received money in 2012 from a number of unions. The Carpenters & Joiners Union, the Laborers’ Union and the International Brotherhood of Electrical Workers each donated more than $1 million. The American Federation of Teachers, the National Association of Letter Carriers and the Service Employees International Union each contributed more than $600,000.

For this campaign cycle, Eychaner had donated $1.5 million through Sept. 8, making him the group’s largest single donor. Simons and hedge fund manager David Sussman had contributed $1 million each.

In 2014, the PAC stepped up its spending as part of its effort to go head-to-head with the conservative Americans for Prosperity.

As of Sept. 8, the PAC had spent a total of $8.55 million — including nearly $1.5 million to help Rep. Nick Rahall defend his seat in West Virginia’s 3rd congressional district against Republican challenger Evan Jenkins. The PAC had spent nearly $1.9 million opposing Jenkins and $477,123 supporting Rahall. The House Majority PAC also had spent over $500,000 each opposing three Republican candidates in Florida, Arizona, and New York.